Acoustic horn



July 30, 1929. M. ABRAHAMS ACOUSTIC HORN Filed Sept. 13, 1926 INVENTOR. x14 Zrzzfia BY G ATTORNEY Patented July 30, 1929.

MAX ABRAHAMS, OF NEW YORK, N. Y.

ACOUSTIC HORN.

Application filed September My invention relates broadly to loud speakers for radio broadcast reproduction and more particularly to a construction of acoustic horn for radio loud speakers.

One of the objects of my invention is to provide a construction of acoustic horn for radio broadcastreproduction in which a relativcly long vibratory air column may be provided at the same time thatthe horn may be housed within small over all compass.

Another object of my invention is to provide an acoustic horn of spiral formation wherein a plurality of sections are assem bled in such manner as to provide a. confined column of air which may be set into vibration by any desired form of sound reproducer for the reproduction of musical notes over a broad range of frequencies.

Another object of my invention is to provide a sound reproducing horn construction of a plurality of sections secured together in such manner that a spiral air column is pro vided having theappearance of a horn of a single length.

Still another object of my invention is to provide a method of joining a plurality of circular shaped sections of a spiral horn for forming a spiral air column for the reproduction of sound over a wide range of frequencies, the walls of the acoustic horn being so formed that there is minimum tendency for vibration or interference with the sound emanating from the sound reproducer connected with the horn.

Other and further objects of my invention will be understood from the specification hereinafter follo ing by reference to the accompanying drawings in which:

Figure 1 is a side elevation of a completed horn constructed in accordance with my invention; Fig. 2 is a perspective view showing the sections of the horn in the process of assembly, the sections being spread for the purpose of more fully explaining the con struction of my invention; Fig. 3 is an end view of the acoustic horn of my invention showing the spiral element of the several sections of the horn; and Fig. 4 is a frag mentary view showing a portion of the horn partially in cross-section with the abutting edges uniting and the oint wrapped to form the spiral air column upon which the sound generator is arranged to op rate.

Herctofore in the art difficulty has been experienced in devising a practical construction of loud speaker horn having a sutli- 13, 1926. Serial No. 135,213.

ciently long air column for the rcproiluctiou of the full range of musical notes encountered in radio broadcast reception. By my invention I provide a construction of acoustic horn having a plurality of sections which may be constructed. in accordance with the principles set forth in Letters Patent of the United States granted to me July 15, 1925 as No. 1,501,032. The sections are joined one to the other and reinforced by tape wrapping for forming the air column upon which. the driver is arranged to operate. The sections are formed on a mould to a desired. shape and then so reinforced at their abutting edges as to form a long spiral column upon which the bell of the horn may L2 attached at one end thereof.

Referring to the drawings in more detail, reference character 1 designates the acoustic horn of my invention. one end thereof being represented at 2 as of relatively small diameter. The diameter of each of the sections which comprise the horn gradually increases as the number of turns increases in the direction of the bell represented at 3. 2 I have shown the sections of the horn rcprescnted at 4t, 5, 6, 7, 8 9. 10., 11, 12 and 13, each circular in contour and each larger in diameter than the next preceding section the section in itself tapering from one diameter to another diameter for forming the spiral air column for the horn. The edges of each of the sections abut and as represented more clearly in Fig. 4 which shows the abutting edges for horn sections 12 and 13, a film of glue H is spread. between the abutting edges of the horn sections 12 and 13. Each of the horn sections is formed from heavy textile fabric which is fleece lined. The cloth sections 12 and 13 therefore each have an inner core of fleece which I have represented at 15, the cloth being impregnated with a suitable tiller, paste or glue, which is subsequently baked for the purpose of hardening. hen the joint between the abutting edges of sections 12 and 13 becomes dry by the drying out of the film 1d: the joint is strengthened by a strip of woven cloth 16 or other material which is impregnated before or subsequentto the application thereof upon the horn sections by means of glue or other hardening material such as shellac, dextrine or other suitable fluids. The joints covered by the tape 16 are then sanded and filled in with paint or filler to conceal the abutting edges of the horn sec- In Fig.

tions. The jointsmay be again subjected to a sanding process and then the entire horn painted or dipped. Suitable ornamentation may be applied to the horn for imparting to the horn the appearance of a one piece continuous spiral. The coatings on the inside and outside of the horn which substantially conceal the independent sections of the horn have been represented by reference character 17.

It will be observed that a rigid mechanical construction of spiral horn may be practically constructed on a quantity production basis in accordance with theprinciple of my invention and that by the wrapping of the horn upon itself in the manner set forth an extremely long air column may be obtained within a very small physical space and the spiral horn thus formed may be readily mounted within a cabinet structure of small size.

I have described one of the preferred methods of constructing the spiral shaped horn, but it will be understood that other methods may be employed and that I intend no limitations upon my invention other than are imposed by the scope of the appended claims.

lVh'at I claim as new and desire to secure by Letters Patent of the United States is as follows: V

1. An acoustic horn comprising a plural ity of sections constituting portions of a spiral each of said sections varying in diameter from one end to an opposite end thereof, the first of said sections having a relatively small average diameter and the last of said sections having a relatively larger average diameter, said sections abutting end to end and secured in abutting relationship forming a multiplicity of convolutions, a bell secured to the last of said sections with the axis of said bell substantially coincident with the axis of said convolutions whereby a spiral air column of substantial length provided with the periphery of said bell lying in a plane substantially perpendicular to an axial line through the convolutions of said horn.

2. an acoustic horn comprising a plurality of sections constituting portions of a spiral each tapering from one diameter to another diameter, adjacent sections having their ends of corresponding diameter in abutment, means for securing said adjacent ends in abutment, a bell connected to the largest of said sections and a coating formed over said sections for substantially concealing the several sections whereby a rigid spiral air column is provided with the periphery of said bell lying in a plane substantially perpendicular-to an axial line through the convolutions of said horn.

3. An acoustic horn comprising a plural ity of fabric sections constituting portions of a spiral, each of said sections having a plurality of difl'erent diameters with adjacent sections having ends of the same diameter secured in abutment, a bell secured to the end section and a coating for all of said sections for substantially concealing the joints between said sections and forming a spirally shaped air column, with the periphry of said bell substantially conforming to the contour of said sections and lying in a plane substantially perpendicular to an axial line through the convolu'tions of said horn.

4. An acoustic horn comprising a plurality of sections constituting portions of a spiral each varying in diameter throughout the length thereof with adjacent ends of succeeding sections secured in abutment, a tape wrapped about abutting ends of said sections bell connected to the section of largest diameter and a coating extending over said tape and said sections for substantially concealing the termination of one sec tion and the beginning of the next succeeding section, said sections lying in planes su stantially parallel with the plane of said bell.

5. An acoustic horn comprising a plurality of sections constituting portions of a spiral each section having gradually varying diameters throughout the length thereof, the successive sections of said acoustic horn each having substantially equal diameters at the ends thereof, said ends being secured in abutment, the first of said sections having a relatively small inlet diameter through which sound vibrations are introduced and the last of said sections having a relatively large diameter forming an outlet and a bell connected to the section of largest diameter for the sound delivered to said inlet, the abutting ends of said sections each being wrapped with impregnated tape and a coating over all of said ections for substantially concealing the termination of one of said sections and the beginning of a' succeeding section, the periphery of said bell substantially conforming to the contour of said sections and lyingin a plane substantially perpendicular to an axial line through the convolutions of said horn.

In testimony whereof I ai'fix my signature.

MAX Austins-ins. 

